Yeah I think I got this from Sandi Metz a long time ago but it's been so valuable to me: "bad code that you never have to modify is good code."
Now when business requirements change and you're constantly sending people into that 1600 line backend function or whatever, it's likely worth it to start doing some refactors. But otherwise if I don't have a good reason to be in there I pretend I don't see it.
I agree with the quote, but this was code that we did modify frequently. It was still ok. 1600 line func is bad, but 1600 line file, well that's what editor splits are for. A lot of app backends don't do much other than shoving stuff into a DB and getting it back.
We'd edit queries or add new HTTP endpoints. Some did a little more than query, maybe hit a cache or external service. There were a few shared helpers, not more than one layer deep though.
Now when business requirements change and you're constantly sending people into that 1600 line backend function or whatever, it's likely worth it to start doing some refactors. But otherwise if I don't have a good reason to be in there I pretend I don't see it.